High compression heads / high performance cams

Discuss all things Model T related.
Forum rules
If you need help logging in, or have question about how something works, use the Support forum located here Support Forum
Complete set of Forum Rules Forum Rules

Topic author
CraigBothwell
Posts: 11
Joined: Fri May 03, 2019 7:05 pm
First Name: Craig
Last Name: Bothwell
* REQUIRED* Type and Year of Model Ts owned: TT truck, Dr. Coupe, Touring
Location: Costa Mess

High compression heads / high performance cams

Post by CraigBothwell » Sat Dec 04, 2021 1:07 pm

I would like very much to talk to any one who is running a Prus high compression
head in combination with a Stipe cam.

Thanks,

Craig Bothwell
bothwell.craig@gmail.com


Scott_Conger
Posts: 6428
Joined: Sun Jan 06, 2019 11:18 am
First Name: Scott
Last Name: Conger
* REQUIRED* Type and Year of Model Ts owned: '13, '15, '19, '23
Location: Clark, WY
Board Member Since: 2005

Re: High compression heads / high performance cams

Post by Scott_Conger » Sat Dec 04, 2021 1:20 pm

I have a Stipe 280, a 7 1/2 degree advanced cam gear and a Waukesha head (vastly improved combustion chamber but little additional compression...easy to crank)

My Impression: WOO HOO!
Scott Conger

Tyranny under the guise of law is still Tyranny

NH Full Flow Float Valves
Obsolete carburetor parts manufactured


Norman Kling
Posts: 4068
Joined: Tue Jan 08, 2019 1:39 pm
First Name: Norman
Last Name: Kling
Location: Alpine California

Re: High compression heads / high performance cams

Post by Norman Kling » Sat Dec 04, 2021 1:36 pm

Whatever you do to increase the power, be sure not to lug the engine at low speeds. Remember that high speed torque does not put extra strain on the crank, however, low end torque puts the most strain on it. You didn't mention what you did to the crankshaft, but I would recommend a SCAT crank.
Norm

User avatar

Henry K. Lee
Posts: 5339
Joined: Sun Jan 06, 2019 11:09 am
First Name: Henry
Last Name: Lee
* REQUIRED* Type and Year of Model Ts owned: Many
Location: South Pittsburg, TN
MTFCA Number: 479
MTFCA Life Member: YES

Re: High compression heads / high performance cams

Post by Henry K. Lee » Sat Dec 04, 2021 2:18 pm

Kevin Prus’s heads are hard to beat, excellent balance in the chambers and get going and cruising very well.

Hank


Bruce Compton
Posts: 576
Joined: Thu Jan 10, 2019 11:23 am
First Name: Bruce
Last Name: Compton
* REQUIRED* Type and Year of Model Ts owned: 1921 Coupe, 1925 Coupe
Location: Kemptville

Re: High compression heads / high performance cams

Post by Bruce Compton » Sat Dec 04, 2021 6:59 pm

I've run Pru, Z, and Reeder heads and the Prus gives the best performance of the three as well as better head gasket sealing surface area over the Z head. All run with a stock cam however.


Art M
Posts: 840
Joined: Wed Jun 19, 2019 12:57 pm
First Name: Art
Last Name: Mirtes
* REQUIRED* Type and Year of Model Ts owned: 1923 Touring
Location: Huron, Ohio
MTFCA Number: 32489
MTFCI Number: 24068
Board Member Since: 2016

Re: High compression heads / high performance cams

Post by Art M » Sun Dec 05, 2021 2:00 pm

Bruce,
Not trying to pick on anyone, just looking for information. Many model t owners who have a .280 cam in their engine claim the engine is stock. I just wondering if your cams are really .25 standard.
Art Mirtes


TXGOAT2
Posts: 6411
Joined: Sun Feb 14, 2021 10:08 pm
First Name: Pat
Last Name: McNallen
* REQUIRED* Type and Year of Model Ts owned: 1926-7 roadster
Location: Graham, Texas
MTFCA Number: 51486
Board Member Since: 2021

Re: High compression heads / high performance cams

Post by TXGOAT2 » Sun Dec 05, 2021 2:35 pm

Does a 280 cam require stiffer valve springs?


Scott_Conger
Posts: 6428
Joined: Sun Jan 06, 2019 11:18 am
First Name: Scott
Last Name: Conger
* REQUIRED* Type and Year of Model Ts owned: '13, '15, '19, '23
Location: Clark, WY
Board Member Since: 2005

Re: High compression heads / high performance cams

Post by Scott_Conger » Sun Dec 05, 2021 3:07 pm

Pat...no, they don't, but some blocks will require a quick countersink inside the block on the lifter bore to allow the lifter enough clearance to make the extra distance it will now travel.
Scott Conger

Tyranny under the guise of law is still Tyranny

NH Full Flow Float Valves
Obsolete carburetor parts manufactured


Les Schubert
Posts: 1311
Joined: Thu Jan 10, 2019 5:47 pm
First Name: Les
Last Name: Schubert
* REQUIRED* Type and Year of Model Ts owned: 27 roadster 13 touring
Location: Calgary

Re: High compression heads / high performance cams

Post by Les Schubert » Sun Dec 05, 2021 3:44 pm

I have run a.320 lift cam and I like stock T springs as the valves will float at about 4200 rpm. This way you have a built in “rev limiter”!
Yes the engine has a counterbalanced pressure oiled A crank and a high compression Sherman head.


Bruce Compton
Posts: 576
Joined: Thu Jan 10, 2019 11:23 am
First Name: Bruce
Last Name: Compton
* REQUIRED* Type and Year of Model Ts owned: 1921 Coupe, 1925 Coupe
Location: Kemptville

Re: High compression heads / high performance cams

Post by Bruce Compton » Sun Dec 05, 2021 6:18 pm

Art,yes, my cams are bone stock and previously used. I'm really thinking about getting a new one, either stock , .270 or .280. Any recommendations? Bruce


Gonenorth
Posts: 130
Joined: Tue Jan 08, 2019 6:04 pm
First Name: Kevin
Last Name: Whelihan
Location: Danbury, WI
MTFCA Number: 30688
Board Member Since: 2008

Re: High compression heads / high performance cams

Post by Gonenorth » Sun Dec 05, 2021 7:02 pm

Have Prus head and Stipe 280 cam in professionally rebuilt engine with a SCAT crank. Also and Ideal Timer(Kossor). Starts easy, runs like a dream in my '26 Touring. I like the combination so well I am building up another engine just like it for my '26 Tudor.

User avatar

Henry K. Lee
Posts: 5339
Joined: Sun Jan 06, 2019 11:09 am
First Name: Henry
Last Name: Lee
* REQUIRED* Type and Year of Model Ts owned: Many
Location: South Pittsburg, TN
MTFCA Number: 479
MTFCA Life Member: YES

Re: High compression heads / high performance cams

Post by Henry K. Lee » Sun Dec 05, 2021 7:51 pm

Perfect combination Kevin, built a few like that.

Hank


greenacres36
Posts: 134
Joined: Sun Sep 27, 2020 3:50 pm
First Name: Brian
Last Name: Williams
* REQUIRED* Type and Year of Model Ts owned: 1926 Tudor, 1915 Runabout
Location: Prospect, Ohio

Re: High compression heads / high performance cams

Post by greenacres36 » Sun Dec 05, 2021 8:12 pm

I have that same combo. Prus head, Scat crank but Chafin 280 cam and I timer. Great combo for sure. Good power, starts very well. I only have one issue. I rebuilt the coils using an ECCT and the magneto he’s putting out about 30 volts, but it runs way better on battery. It seems like you cannot get the proper timing on magneto. It wants to be between notches per se. if there’s a solution for that I am all ears.

I always joke with my friends that they should not call them a high performance cam. They should be considered a more performance cam. That’s always good for a laugh.


TXGOAT2
Posts: 6411
Joined: Sun Feb 14, 2021 10:08 pm
First Name: Pat
Last Name: McNallen
* REQUIRED* Type and Year of Model Ts owned: 1926-7 roadster
Location: Graham, Texas
MTFCA Number: 51486
Board Member Since: 2021

Re: High compression heads / high performance cams

Post by TXGOAT2 » Sun Dec 05, 2021 8:46 pm

I wonder if your magneto has a poor internal ground or a poor connection somewhere in the system...


Norman Kling
Posts: 4068
Joined: Tue Jan 08, 2019 1:39 pm
First Name: Norman
Last Name: Kling
Location: Alpine California

Re: High compression heads / high performance cams

Post by Norman Kling » Sun Dec 05, 2021 9:03 pm

Brian,
Your problem could be the timer. On battery, you begin to build up the current in the coils when the rotor makes first contact and continues to spark until it ends contact with that segment. However on magneto, the peak voltage and current occurs when the magneto reaches the peak of the sine wave. So if your timer is not making good contact at that point you will misfire. And it is even possible that if the timer is set in certain positions, you could one coil firing more advanced than another.
Norm


Art M
Posts: 840
Joined: Wed Jun 19, 2019 12:57 pm
First Name: Art
Last Name: Mirtes
* REQUIRED* Type and Year of Model Ts owned: 1923 Touring
Location: Huron, Ohio
MTFCA Number: 32489
MTFCI Number: 24068
Board Member Since: 2016

Re: High compression heads / high performance cams

Post by Art M » Mon Dec 06, 2021 9:11 pm

I would check the ignition switch first.

Then try a non electronic timer.

Then a different set of coils known to be good. You might have a friend who could loan a set.

From there it could be the magneto.

Was the cam timing changed by 7 degrees like some people do?

Keep us informed on your progress. Wish you lived closer,
I like working on challenges that this. Except it reminds me of working, which was more than 21 years ago.

Art Mirtes


Les Schubert
Posts: 1311
Joined: Thu Jan 10, 2019 5:47 pm
First Name: Les
Last Name: Schubert
* REQUIRED* Type and Year of Model Ts owned: 27 roadster 13 touring
Location: Calgary

Re: High compression heads / high performance cams

Post by Les Schubert » Tue Dec 07, 2021 9:40 am

I am surprised by the I Timer being run off of the magneto. I thought they were only meant to be used powdered by the battery. Learn something new every day!


Original Smith
Posts: 3284
Joined: Tue Jan 08, 2019 10:43 am
First Name: Larry
Last Name: Smith
* REQUIRED* Type and Year of Model Ts owned: 13 Touring, 13 Roadster, 17 Coupelet, 25 Roadster P/U
Location: Lomita, California
MTFCA Number: 121
MTFCA Life Member: YES
MTFCI Number: 16310

Re: High compression heads / high performance cams

Post by Original Smith » Tue Dec 07, 2021 10:09 am

I have been driving T's all of my adult life. I would love to have one of Kevin's heads, but not until they are made of cast iron. I also run a Stipe cam. but wish he would make BOTH designs as Ford did. I now have an early cam in my '25, and a late cam in my '13. I don't feel like tearing the engines down just to have the correct looking cam in my cars!


TXGOAT2
Posts: 6411
Joined: Sun Feb 14, 2021 10:08 pm
First Name: Pat
Last Name: McNallen
* REQUIRED* Type and Year of Model Ts owned: 1926-7 roadster
Location: Graham, Texas
MTFCA Number: 51486
Board Member Since: 2021

Re: High compression heads / high performance cams

Post by TXGOAT2 » Tue Dec 07, 2021 11:47 am

RE: I-TIMER: Does the I-Timer run on Magneto?//////////////

Yes! Start on battery, Run on battery OR Magneto just like the stock timer

Can I get free starts using the I-Timer?

Yes! Same as a stock timer

Can I start on magneto using the I-Timer?

No, the I-Timer will not start on magneto ////////////// (Kosser I-Timer Website)


Les Schubert
Posts: 1311
Joined: Thu Jan 10, 2019 5:47 pm
First Name: Les
Last Name: Schubert
* REQUIRED* Type and Year of Model Ts owned: 27 roadster 13 touring
Location: Calgary

Re: High compression heads / high performance cams

Post by Les Schubert » Tue Dec 07, 2021 8:15 pm

Larry
The first production run of Prus heads were cast iron. I bought then and have one. No it’s not for sale!

Post Reply Previous topicNext topic